Dr. Oscar Benavente, neurologist and research director of the Stroke and Cerebrovascular Health Program at VCH and member of the Brain Research Centre at UBC and the VCH Research Institute
How best to prevent a stroke or stroke reoccurrence is an important concern for cardiac and stroke patients and their caregivers.
Now, an international team led by Dr. Oscar Benavente, neurologist and research director of the Stroke and Cerebrovascular Health Program at Vancouver Coastal Health and professor of Neurology at the University of British Columbia, has shown a potential treatment – a combination of aspirin and clopidogrel, both common blood thinners – does not prevent recurrence of a common type of stroke, and may even pose serious risks.
The results of their large scale study were published online, August 29 2012, in the New England Journal of Medicine.
The research team sought to determine if a combination of a blood thinner, clopidogrel (known commercially as Plavix) and aspirin, an accepted standard antiplatelet therapy, would lower the recurrence of lacunar strokes more than aspirin alone.
A lacunar stroke is a type of stroke that occurs when one of the arteries that provide blood to the brain’s deep structures becomes blocked. They account for 25 percent of ischemic strokes – death of brain tissue caused by a blockage in the blood vessels – which tend to occur at a younger age and usually strike a person repeatedly. This type of stroke can typically cause mild disability, including cognitive impairment and dementia, and are particularly frequent in Hispanics. The combination of aspirin and clopidogrel was thought to hold promise as it is already used to prevent vascular events in patients with acute coronary syndromes.
The study, the first controlled trial to examine secondary prevention in lacunar stroke, involved 3,020 patients from 82 sites in North America, Latin America, and Spain who were followed for several years. All patients had suffered a recent lacunar stroke as identified by MRI.
The results found that the two-drug combination (known as “dual antiplatelet therapy”) did not significantly reduce the risk of recurrent stroke, and in fact significantly increased the risk of bleeding and death compared to people who were taking aspirin alone or aspirin combined with a placebo. The trial was ended prematurely because of the results and possible harm.
“Previous randomized trials assessing the effect of clopidogrel alongside aspirin for different types of strokes, and in patients with coronary artery disease, did not show an overall increase in mortality, so our results are a bit surprising,” said Dr. Benavente, who is also a member of the Brain Research Centre at UBC and the VCH Research Institute. “It’s a finding that supports the hypothesis that the role of platelets and thrombosis – the formation of clots in blood vessels – may not be the same in different types of strokes. The results of our research support the current guidelines for secondary stroke prevention: the use of either aspirin or clopidogrel, or the approved combination therapy of aspirin and dipyridamole (known commercially as Persantine).”
The study was monitored by an independent data and safety monitoring committee selected by the U.S. National Institute of Neurological Disorders, which funded the study. Support was also provided by Sanofi-Aventis and Bristol-Myers Squibb, which donated the clopidogrel and matching placebo used in the study.
Dr. Benavente is leading a $66-million international study funded by the U.S. National Institutes for Health seeking to reduce recurrence of lacunar strokes and to minimize the consequences. Additional results are expected later this year, which will help determine the optimal combination of blood pressure control and anti-clotting therapy. More information on SPS3 is available at www.sps3.org.
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